[WASM] Implement ConstrainedOnceSequence

libraries/stdlib/wasm/src/kotlin/Sequences.kt

@@ -5,8 +5,12 @@
 
 package kotlin.sequences
 
-internal actual class ConstrainedOnceSequence<T> : Sequence<T> {
-    actual constructor(sequence: Sequence<T>) { TODO("Wasm stdlib: ConstrainedOnceSequence") }
+internal actual class ConstrainedOnceSequence<T> actual constructor(sequence: Sequence<T>) : Sequence<T> {
+    private var sequenceRef: Sequence<T>? = sequence
 
-    actual override fun iterator(): Iterator<T> = TODO("Wasm stdlib: ConstrainedOnceSequence")
+    actual override fun iterator(): Iterator<T> {
+        val sequence = sequenceRef ?: throw IllegalStateException("This sequence can be consumed only once.")
+        sequenceRef = null
+        return sequence.iterator()
+    }
 }